Answer:
The correct option is C (marginal revenue is less than $9)
Explanation:
If the price of a commodity is lowered because you have some kind of monopoly over the industry, this shows that the marginal revenue is lower than the new selling price. This is simply because marginal revenue is that revenue gained when you produce one more unit of a product, and hence there is no way that this value would be greater than the new selling price. You would be selling at a loss if you do so.